The present invention relates to an air belt apparatus in which a belt for constraining an occupant to a seat is inflated with a gas supplied from an inflator in case of a car collision.
An air belt apparatus in which a bag is accommodated in the inside of a seat belt so that the bag is inflated in case of a car collision to constrain an occupant softly, is already known, for example, by a Japanese Patent Unexamined Publication No. Hei. 6-56001.
The belt of the aforementioned air belt apparatus has a webbing on its outside, and a bag in its inside. The webbing has a warp-knitting mesh structure so that the webbing follows the inflation of the bag to increase the diameter of the webbing and, at the same time, contract the webbing of the same. Accordingly, a surface of the webbing is so large-meshed as to be felt rough. The feeling obtained when an upper portion of a shoulder belt touches the nape of the occupant's neck directly without interposition of any clothes is not always pleasant.
On the other hand, a vent hole is provided in a bag of such an aforementioned air belt apparatus in such a manner that an excess of gas is discharged through the vent hole after the bag is inflated to thereby adjust the inner pressure of the bag to an appropriate value.
However, if the vent hole is blocked by the occupant's body when the occupant is constrained by the belt, there is a possibility that the gas is not discharged smoothly. There is a problem that it is difficult to discharge an excess of gas in appropriate timing to thereby adjust the inner pressure of the bag.
The present invention is designed on the aforementioned circumstances.